Identification and authorship
Liber de principiis motus processivi (“Book on the Principles of Progressive Motion”) is a Latin treatise of natural philosophy by Albertus Magnus (Albert the Great, c. 1200–1280), the Dominican friar, bishop, and philosopher known to the later tradition as Doctor universalis. Albert was among the most learned figures of the thirteenth century, a teacher at Paris and Cologne, and the master of Thomas Aquinas. He is remembered above all for his vast and deliberate program of making the whole of Aristotelian science available and intelligible to the Latin West, producing paraphrase-commentaries on Aristotle’s logic, metaphysics, ethics, and—most extensively—natural philosophy, into which he interpolated his own “digressions” as well as material drawn from Greek, Arabic, and Jewish sources.
The subject named in the title, motus processivus, is “progressive” or locomotive motion: the change of place by which an animal moves itself from one location to another (walking, crawling, flying, swimming), as distinguished from other kinds of change and from motion in general. The work therefore belongs to the branch of Albert’s natural philosophy that treats living things and their activities, and it corresponds in subject to the short Aristotelian zoological treatises concerned with animal movement—the material transmitted under the titles De motu animalium and De incessu (progressu) animalium.
Subject and place in Albert’s Aristotelian project
Albert’s natural-philosophical corpus is organized as a running exposition of the Aristotelian sciences of nature, moving from general principles of change and body (the Physica, De caelo et mundo, De generatione et corruptione, the Meteora) through the study of soul and the psychological functions (De anima and the Parva naturalia) to the study of plants and animals (De vegetabilibus and the large De animalibus). Within this ordered scheme, the Liber de principiis motus processivi takes up specifically the question of what is required, in the animal, for it to be the source of its own local motion.
The inquiry is at once physiological and psychological, in keeping with Aristotle’s own treatment. On the one side it concerns the bodily conditions of self-movement: the necessity of an internal point of rest or support against which motion can be exerted, the articulation of limbs at joints so that parts can bend and be extended, the paired and lateral arrangement of the organs of movement, and the instrumental role of the members that push and pull the body forward. On the other side it concerns the mover proper to the animal—the soul as principle of motion—and how the object of desire, apprehended as good or to be pursued or avoided, functions as that which first sets the living thing in motion. In treating these matters Albert follows the characteristic aim of his Aristotelian works: to expound the doctrine fully, to supply causes, and to reconcile or adjudicate the views of his authorities.
Significance and transmission
The treatise is a genuine part of Albert’s authentic corpus and is included among his Opera omnia. In the modern critical edition of Albert’s works undertaken at the Albertus-Magnus-Institut (the Cologne edition, Editio Coloniensis), De principiis motus processivi was edited by Bernhard Geyer. As one of the smaller, specialized pieces of Albert’s natural science, it is significant chiefly as evidence of the thoroughness with which he sought to cover the entire Aristotelian program, extending even to the brief treatises on animal locomotion, and as a witness to how thirteenth-century Latin scholars integrated Aristotle’s biological and psychological doctrines of self-motion into a unified philosophy of nature. Its importance lies less in independent doctrinal novelty than in its place within that comprehensive encyclopedic enterprise for which Albert became famous and which decisively shaped the reception of Aristotle in the medieval universities.
